Relatively inexpensive solid state pressure transducers are routinely used for monitoring the cardiovascular pressure and other fluid pressures of patients who are hospitalized or undergoing medical treatment and diagnostic tests. The accuracy of these pressure monitoring devices is subject to change, possibly producing substantial errors in the indicated pressure. In certain critical procedures where the patient's physiological state must be accurately monitored, errors in a pressure transducer connected to monitor a vital body function may become very significant, even life-threatening in their consequences.
Calibration of such pressure monitoring devices may be accomplished by comparison against a reference standard to which the same fluid pressure is applied. Ideally, the pressure transducer under test should be calibrated at a minimum of three reference points, including its full scale rated pressure, to determine its accuracy and linearity. Although a more accurate reference standard such as an air piston gauge may be used, a digital readout pressure reference standard is available for this purpose. The device is approximately the same size as a hand calculator and weighs several pounds. This reference standard is designed to supply a variable calibration pressure to a pressure transducer under test. Adjustment of the calibration pressure is effected by turning a thumb wheel to vary the fluid displacement of a piston in a cylinder.
Although relatively small, the above-described prior art pressure transducer reference standard is too bulky to be conveniently carried on the person of a nurse or medical technician. In addition, its cost makes it impractical to equip each individual having a need to check pressure monitors with the device. Unfortunately, experience has shown that unless a reference standard is readily at head, pressure transducers used in critical medical applications are unlikely to be calibrated as often as should be. With the growing concern about medical malpractice, it has become very important for hospitals, doctors and health care personnel to take all reasonable steps to ensure the patient's wellbeing. Such reasonable steps would probably include frequently checking the accuracy of pressure monitoring devices used to monitor critical bodily functions.
In consideration of these concerns, it is an object of the present invention to provide a low cost, portable calibration reference, useful for calibrating pressure monitoring devices.
It is a further object to provide an easily adjusted calibration pressure that may be readily input to the pressure monitoring transducer.
A still further object is to provide a known calibration reference pressure with a compact device, sufficiently small and lightweight to be carried on the person of a user.
Yet a still further object is to provide a digital display on a calibration reference standard, indicating the pressure of the fluid supplied to calibrate the pressure monitoring device.
These and other objects of the invention will be apparent from the description of the preferred embodiment of the invention in relation to the attached drawings.